Make-up cosmetics, such as powder foundation, rouge, eye shadow, and lipstick, are commonly prepared with main constituents, such as pigments, extender pigments, binders, and other additives and are used to enhance attractiveness and to improve self-esteem.
However, conventional cosmetics do not last for extended periods when applied to the skin. Applied cosmetics, over time, tend to unevenly spot, change color, and even come off a skin surface primarily because of their interaction with sebum and perspiration with loss of adhesion. The extent of such degradation of applied cosmetics is dependent upon individual skin type, as well as ambient environmental factors such as humidity and temperature.
In the past, in order to prevent degradation of cosmetic make-up resulting from perspiration and in order to improve the wear and long-lasting characteristics thereof, the surface of pigments and extender pigments, used in the cosmetics were coated with silicone or metal soap to render such materials hydrophobic (“hydrophobidization”). While use of the hydrophobidized pigments and extender pigments reduced color drift resulting from interaction with perspiration, wear and long-lasting characteristics were not effectively improved since the hydrophobized cosmetics lacked effective skin adhesion.
Surface-coating on pigments and extender pigments with amino acid compounds, lecithin, and other similar materials has been suggested to improve longevity. However, while these surface-treatments improve the hydrophobicity and tactile feel of pigments, wear and long-lasting characteristics could not be effectively improved because of lack of adhesion to the skin.
Surface-coating with fluorocompounds has been also suggested since it provides both hydrophobicity and lipophobicity to pigments and extender pigments, whereby color drift due to perspiration and sebum is reduced. Again however, they did not improve wear and long-lasting characteristics since they did not improve adhesion to the skin.
Use of additives, such as animal oils (squalene and lanoline), fatty acids (myristic acid and stearic acid) and their esters, and glyceride of saturated fatty acids, to cosmetic preparations has been also suggested to improve wear. However, these additives are not easily dispersed on the surface of pigments to form uniform coating as they tend to agglomerate. Though these additives slightly improve tactile feel and adhesion to the skin nevertheless they are not very effective in improving the hydrophobicity, and wear and long-lasting characteristics.